How to reproduce:
# mount -t cgroup -o memory xxx /cgroup
# mkdir /cgroup/tmp
# ./cgroup_event_listener /cgroup/tmp/cgroup.event_control abc
^C
# rmdir /cgroup/tmp
# cat /proc/cgroups | grep memory
memory 2 2 1 (should be "2 1 1")
# umount /cgroup
(failed!)
Using a single goto label to cleanup multi failure paths can
get things wrong quite easily, while multi labels makes the
code cleaner.
Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
---
cgroup.c | 39 ++++++++++++++++++---------------------
1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/kernel/cgroup.c.orig b/kernel/cgroup.c
index d142524..6ff40f6 100644
--- a/kernel/cgroup.c.orig
+++ b/kernel/cgroup.c
@@ -3029,10 +3029,10 @@ static void cgroup_event_ptable_queue_proc(struct file
*file,
static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
- struct cgroup_event *event = NULL;
+ struct cgroup_event *event;
unsigned int efd, cfd;
- struct file *efile = NULL;
- struct file *cfile = NULL;
+ struct file *efile;
+ struct file *cfile;
char *endp;
int ret;
@@ -3058,46 +3058,46 @@ static int cgroup_write_event_control(struct cgroup
*cgrp, struct cftype *cft,
efile = eventfd_fget(efd);
if (IS_ERR(efile)) {
ret = PTR_ERR(efile);
- goto fail;
+ goto out_free_event;
}
event->eventfd = eventfd_ctx_fileget(efile);
if (IS_ERR(event->eventfd)) {
ret = PTR_ERR(event->eventfd);
- goto fail;
+ goto out_put_efile;
}
cfile = fget(cfd);
if (!cfile) {
ret = -EBADF;
- goto fail;
+ goto out_put_eventfd;
}
/* the process need read permission on control file */
ret = file_permission(cfile, MAY_READ);
if (ret < 0)
- goto fail;
+ goto out;
event->cft = __file_cft(cfile);
if (IS_ERR(event->cft)) {
ret = PTR_ERR(event->cft);
- goto fail;
+ goto out;
}
if (!event->cft->register_event || !event->cft->unregister_event) {
ret = -EINVAL;
- goto fail;
+ goto out;
}
ret = event->cft->register_event(cgrp, event->cft,
event->eventfd, buffer);
if (ret)
- goto fail;
+ goto out;
if (efile->f_op->poll(efile, &event->pt) & POLLHUP) {
event->cft->unregister_event(cgrp, event->cft, event->eventfd);
ret = 0;
- goto fail;
+ goto out;
}
/*
@@ -3116,16 +3116,13 @@ static int cgroup_write_event_control(struct cgroup
*cgrp, struct cftype *cft,
return 0;
-fail:
- if (!cfile)
- fput(cfile);
-
- if (event && event->eventfd && !IS_ERR(event->eventfd))
- eventfd_ctx_put(event->eventfd);
-
- if (!IS_ERR_OR_NULL(efile))
- fput(efile);
-
+out:
+ fput(cfile);
+out_put_eventfd:
+ eventfd_ctx_put(event->eventfd);
+out_put_efile:
+ fput(efile);
+out_free_event:
kfree(event);
return ret;
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